This invention relates to particle detection, and more particularly to apparatus and method for visualizing suspended particles in a fluid.
Certain known apparatus for detecting particles suspended in a fluid such as water within a vessel commonly rely upon scattering of an incident beam of light in diverse directions off axis of the incident beam for various forms of optical detection at diverse angular positions about the axis of the incident beam (See, for example, U.S. Pat. Nos. 3,858,851 and 4,623,252). Such particle detection apparatus tends to rely upon elaborate optical detection schemes to implement quantifying and qualifying techniques used to determine the number and size of particles per unit volume. Accurate operation of such particle detection apparatus may be limited to sufficiently low particle density,or to sufficiently small size range of particles present in the fluid to avoid overloading or otherwise exceeding the detection and computational capabilities of such particle-detection apparatus. In such circumstances, pre-filtering or dilution processing of a test sample may be required in order to bring particle densities or particle size variations into operable ranges. In order to screen test samples for proper operational parameters a test sample may have to be previewed for conformance with operational limits of such elaborate particle detection apparatus in order to determine whether pre-filtering or dilution or other pre-test processing of a test sample may be required.
Accordingly, with illustrated embodiments of the present invention, a visualizing apparatus and method facilitate conducting quick initial visual evaluations of test samples for conformance with operational testing limits, or for other visual factors, with capability to provide approximate analyses of particle densities and particle sizes down to about one micron particle size in reliance upon only unaided eyesight of an operator. Embodiments of the apparatus and method include a collimated beam of light that is directed into a fluid sample along one axis, and include a viewing port aligned along a skewed axis for visualizing only light scattered from the incident light beam by suspended particles. The visualization axis for light thus scattered by suspended particles may be oriented with an orthogonal component aligned along the direction of light propagation of the incident light beam in order to facilitate viewing forwardscattered light from a test sample. Any portion of the incident light beam that traverses the fluid sample is absorbed at a location out of alignment with the skewed visualizing axis. The incident light beam may be repetitively scanned through the fluid sample along various paths in order to facilitate visualization of a maximum distribution of suspended particles throughout the fluid test sample. Similar scanning of an incident light beam through a population of reference samples positioned in close proximity to the test sample promotes rapid visual comparisons and estimations of sample sizes and densities via comparative visualizations through the viewing port of scattered light from both reference sample and test sample.